An electromechanical actuator 100 (FIG. 1a) for a valve 110 comprises mechanical means, such as springs 102 and 104, and electromagnetic means, such as electromagnets 106 and 108, for controlling the position of the valve 110 by means of electric signals.
The rod of the valve 110 is applied for this purpose against the rod 112 of a magnetic plate 114 located between the two electromagnets 106 and 108.
When current flows in the coil 109 of the electromagnet 108, the latter is activated and attracts the magnetic plate 114, which will come into contact with it.
The simultaneous displacement of the rod 112 enables the spring 102 to bring the valve 110 into the closed position, the head of the valve 110 coming against its seat 111 and preventing the exchange of gas between the interior and the exterior of the cylinder 116.
Analogously (not shown), when current flows in the coil 107 of the electromagnet 106 (the electromagnet 108 being deactivated), it is activated and attracts the plate 114, which comes into contact with it and displaces the rod 112 by means of the spring 104 such that the rod 112 will act on the valve 110 and brings the latter into the open position, the head of the valve being moved away from its seat 111 to permit, for example, the admission or the injection of gas into the cylinder 116.
When the electromechanical actuator 100 is functioning correctly, the valve 110 alternates between fixed open and closed positions, called switched positions, with transient displacements between these two positions. The open or closed state of a valve will hereinafter be called the “switched state.”
An actuator 150 (FIG. 1b) may also be equipped with magnets 168 (electromagnet 158) and 166 (electromagnet 156) intended to reduce the energy necessary for maintaining the plate 164 in a switched position, i.e., in contact with one of the electromagnets.